Machine for planting and sealing furrow with transparent material

ABSTRACT

A field-cultivating machine which while moving across a field forms a selectively shaped furrow in the soil, prepares the soil for planting, plants seeds or seedlings in the furrow, and then forms a closed chamber by sealing a strip of plastic film over the top of the furrow and into the soil along both sides which by limiting temperature range in the furrow, promotes seed germination and accelerates plant growth. The machine is drawn by a tractor and includes a plow and furrow-shaping structure which support the sides of the furrow while planting and sealing are completed. The soil is prepared by devices which introduce fertilizer, water, insecticide and herbicide into the furrow and then the seeds or seedlings are planted in the bottom of the furrow. A strip of translucent plastic film is continuously laid and supported over the furrow by at least one surface while the edges of the film are pressed into preformed grooves extending along the sides of the furrow. Soil discs place soil on the film edges while they are held in the grooves and packing wheels press the soil firmly against the film sealing the edges. Shaped slits are mechanically made in the film at intervals over the furrow to allow ingress of water and a limited exchange of air. This invention relates to an apparatus and method for creating a plurality of plant growth chambers in an ordinary field in which the temperature is substantially regulated for the purpose of promoting seed germination and plant growth for an initial critical growth period. In greater detail, this invention teaches the advantages of use of translucent mulch such as plastic film to seal the top of field furrows, which during the same operation, are formed, prepared for seeding and planted for the purpose of enhancing plant growth by eliminating seed and plant injury caused by frost and other harsh weather conditions.

United States Patent Inventor Alfred D. Hoadley Napoleon, Ohio Appl. No.781,911 Filed Dec. 6, 1968 Patented Feb. 2, 1971 Assignee Campbell SoupCompany Camden, NJ. a corporation of New Jersey MACHINE FOR PLANTING ANDSEALING F URROW WITH TRANSPARENT MATERIAL 12 Claims, 6 Drawing Figs. US.Cl. 11 Ill, 111/3, 47/9,111/85, 47/26, 172/701 Int. Cl. ..A0lg 13/02,AOlc 7/18 FieldofSearch Ill/1,6,7, 85, Methods, Furrow Planting; 47/ 1,9, 26; 172/123, 701

References Cited 9 UNITED STATES PATENTS 2,078,872 4/ 1937 Pfeiffer 47/93,180,290 4/1965 Kappelmann et a1. Ill/85 3,293,797 12/1966Kappelmannetal. 3,353,297 l1/1967 Gervais Primary Examiner-Robert E.Bagwill Attorney-Howson & Howson plastic film over the top of the furrowand into the soil along both sides which by limiting temperature rangein the furrow, promotes seed germination and accelerates plant growth.The machine is drawn by a tractor and includes a plow and furrowshapingstructure which support the sides of the furrow while planting andsealing are completed. The soil is prepared by devices which introducefertilizer, water, insecticide and herbicide into the furrow and thenthe seeds or seedlings are planted in the bottom of the furrow. A stripof translucent plastic film is continuously laid and supported over thefurrow by at least one surface while the edges of the film are pressedinto preformed grooves extending along the sides of the furrow. Soildiscs place soil on the film edges while they are held in the groovesand packing wheels press the soil firmly against the film sealing theedges. Shaped slits are mechanically made in the film at intervals overthe furrow to allow ingress of water and a limited exchange of air.

PATENIED FEBZ |sm SHEET 1 [IF 2 INVENTOR. Alfred D. Hoodley WAD'MATTORNEY.

MACHINE FOR PLANTING AND SEALING FURROW WITH TRANSPARENT MATERIAL Thisinvention relates to an apparatus and method for creating a plurality ofplant growth chambers in an ordinary field in which the temperature issubstantially regulated for the purpose of promoting seed germinationand plant growth for an initial critical growth period. In greaterdetail, this invention teaches the advantages of use of translucentmulch such as plastic film to seal the top of field furrows, whichduring the same operation, are formed, prepared for seeding and plantedfor the purpose of enhancing plant growth by eliminating seed and plantinjury caused by frost and other harsh weather conditions.

PRIOR ART The use of mulches composed of various materials to promoteplant growth has been known in the industry for many years. Althoughsometimes finding special use in protecting grown shrubbery from windsor delicate plants such as tobacco from the suns rays, mulches are moregenerally placed directly on the ground. Used in this way mulch retardsweed growth around the cultivated plant, conserves moisture in the soiland tends to store heat in the soil. Heavy mulch can be used to supportseedlings in the proper. position when planted by hand or machine suchas in the case of pineapple Mechanical harvesting is made more efiicientbecause the plants and the fruit, such as tomatoes, mature earlier inthe late summer, thus permitting the farmer to delay the harvest untilthe optimum quantity of fruit matures in each field without riskingfrost damage due to late harvesting. Similarly, because the crop maturesearlier, manual harvesting can be used more efficiently when it iscombined with mechanical harvesting or used as the sole means ofcollecting the crop.

Larger yields are possible because the extended growing season offersgreater plant population by allowing fruit to be grown from inexpensiveseeds which are sown in larger quantity than are planted seedlings peracre.

Similarly, the cost of transplanting seedlings may be reduced or eveneliminated as a large crop may be safely grown from seeds and harvestedat an earlier time in the summer. The above outlined advantages findspecific application in the tomato crop planting in northern stateswhere seed planting may be advanced about one month in the spring butthe invention has valuable utility in southern states by allowing twogrowing seasons.

slips. Mulches may be formed, for example, from leaves,

paper, cotton fabrics, canvas and lately polyethylene plastic film andas they are normally employed to suppress weed growth, they are opaqueto prevent passage of sunlight. Machines for automatically feeding andplacing mulches on the ground for the purposes described have beenavailable for many years and, as an example, reference is made to U.S.Pat. No. 1,436,139 to L. E. Bailey and No. 1,471,796 to N. B Mc- Guireet al. In most instances where mulch is used, the soil is flattened andsmoothed to receive the mulch and may even be shaped to have atransverse,- convex surface as shown in U.S. Pat. No. 3,184,889 to C. E.Gray et al. It is clear, however, that the use of mulch in this mannerpromotes plant growth by retarding weeds by covering soil adjacent theplant and by conserving moisture in the soil but does nothing to protectthe seed or seedlings from adverse weather conditions. When mulch isplaced on the ground, seeds or seedlings are planted through the mulchinto the soil allowing weather to reach the seed and surrounding soiland the mulch offers no protection once the plant rises from the ground.

Some attempts have been made to use mulch to protect seedlings bycovering the plants after they germinate and rise above the level of thesoil. In U.S. Pat. No. 2,078,872 to A. Pfieffer arched paper is placedon the ground over the plants. Similarly, in U.S. Pat. No. 3,352,297 toA. C. Gervais, a transparent plastic is placed over a row of plants byforming a pair of soil banks on both sides of the row higher than theplants and placing the film on these banks. Although the Pfeifferapparatus protects rows of plants against adverse weather conditions, itprevents growth by being impervious to the sun's rays. The Gervaisapparatus assumes a row of plants and is limited to those fieldconditions which allow soil to be scraped into banks after planting hasoccurred. Further, Gervais does not show means for initially preparing afurrow within the soil, preparing the soil, planting seed and thensealing the furrow to form a temperature controlled chamber in whichseed can more quickly genninate and develop.

Therefore, it is the primary object of this invention to provide a fieldgrowth chamber of the character described which, by limiting the weatherextremes, extends the effective growing season by permitting both seedsto be planted about one month earlier in the spring in northern areas ofthis country. Early planting results in earlier harvesting which, inturn, offers several specific benefits including more efficientmechanical harvesting, large yields, reduced costs, and othere'fficiencies.

It is a further object of this invention to provide a workable andeconomical apparatus and process which in a single pass across anunprepared field will form and shape one or more furrows of suitabledepth and shape, prepare the soil for planting and introduce water,fertilizer and similar conditioners, plant seeds and then effectivelylay and seal in the soil a transparent plastic mulch across the top ofthe furrow which will protect the seeds against frost and other harshweather conditions and promote their germination and development.

In summary, this invention teaches apparatus and method for protectingseeds during germination and initial growth period right in the field athighly economical cost by combining in a single machine the functions offorming a suitable furrow, preparing the soil in the furrow for maximumgrowth, planting seeds and then sealing the furrow to form a chamberwherein a relatively high temperature is maintained by allowing the sunsrays to heat the soil and air within the chamber and preventing cold airfrom entering the chamber. The apparatus of this invention discloseshighly efficient means for sealing the furrow covering, translucentmulch in the soil so that neither high winds nor heavy rains can removeit until the season has progressed and the chamber is no longernecessary. Further, by means of shaped perforations in the film, rainwater passes into the soil while moisture evaporating from the soil iscondensed on the inside of the film and drops again into the soil.

In greater detail, the preferred process of this invention in- I cludesthe steps of forming a shaped furrow in an unprepared field suitable forthe nature of the plant and the type of soil, planting the seed in thefurrow while enhancing the soil by fertilizer, water and the like,feeding a transparent mulch across the furrow, creating a pair ofgrooves parallel to and adjacent the top edge of the furrow, installingthe side edges of the film in the grooves, laterally moving and packingthe soil into the grooves to lock and seal the film edges whilesupporting the film across the furrow to prevent lateral movement whichwould displace the film and pull down the soil into the furrow. And,finally, slitting the film at desired locations to allow rain water andlimited amounts of air to pass through into .the chamber created.

Although the apparatus and process of this invention may assume severalembodiments, the preferred form as it is now in use is described belowand shown in the drawings, which are made a part hereof by reference,wherein:

FIG. 1 is a side elevational view of one form of the apparatus of thisinvention;

FIG. 2 is a sectional view from above taken along the lines and arrows2-2 of FIG. 1 with additional structure shown in broken lines; and

FIGS. 3-6 are sectional views of the apparatus shown in FIG. 1 lookingforward and taken at selected locations as indicated by the lines andarrows in FIG. 1.

The preferred form of the apparatus of this invention comprises amovable vehicle which in the present instance is mounted on four wheels22 in the corners and drawn in one direction by a tractor not shown bymeans of a standard tractor hitch 9 shown in broken lines at the leftend of the vehicle in FIG. 2. The vehicle is generally constructed witha supporting frame 10 approximately 8 feet wide and 12 feet longcomposed of generally rectangularly joined longitudinal beams 12 andcrossbeams 13 which support specialized apparatus therebeneath. Theframe 10 is supported in the front by crossbeam 14 fixedly mounted inbrackets 16 and in the rear by crossbeam 18 mounted for limited rotationin brackets 20. Four wheels 22 support and are joined to the two beamsby separate apparatus which permits the frame, in the rear, to be raisedor lowered in relation to the ground and, in the front, permits thefurrow-shaping structure to be vertically positioned to form a furrow ofdesired depth and size. The front end of the frame is lifted for generalpurposes at the hitch 9 by standard apparatus mounted on the tractor notshown.

In front, the two wheels 22 are each mounted on a hub 24 in an arm 26which is pivotally joined to yoke 28 fixedly attached to crossbeam 14. Athreaded crank 30 threads through a pivoting nut 32 (not shown) mountedin yoke 28 and is pivotally attached to arm 26 to control the positionof arm 26 about its pivoted connection with yoke 28. Clockwise rotationof crank 30 causes arm 26 to pivot downwardly in relation to yoke 28thereby raising beam 14, frame 10 and, particularly, plow 52 and furrowstructure 56 in relation to the soil. Of course, the same assembly isfound on the opposing front side of the vehicle.

The rear wheels 22 are mounted differently and controlled by hydraulicpressure operated from the drawing tractor. By means of thehydraulically controlled rear end of the vehicle and the lifting of thefront end through hitch 9, the frame and attached apparatus can bequickly lifted clear of the soil so that the vehicle can be readilytransported or positioned in a field to form a new furrow. Each rearwheel 22 is mounted on a hub 34 in a yoke 36 which becomes extended assteering shaft 38, which is supported for limited rotation in collar 40.Collar 40 is attached to a bracket 42 which is attached to crossbeam 18mounted in brackets 20. A standard hydraulic piston assembly 44pivotally mounted on the frame at one end and attached to bracket 46 onthe other and therethrough to beam 18 controls rotary movement of beam18 and, through bracket 42 and yoke 36 on each side of the vehicle,raises and lowers the frame 10 in relation to the ground. The hydraulicassembly 44 is powered by a source of hydraulic pressure on the tractor(not shown) which passes through hoses 41 partially shown in the rear ofthe vehicle.

Steering of the vehicle is accomplished by slight turning of the rearwheel by means of connecting steering links extending rearwardly fromthe tractor to a common transverse arm 39 (FIG. 2) which controls shafts38 attached to each rear wheel through links 37. In detail rear wheelshafts 38 are controlled by links 37 which are attached to transversesteering arm 39 which in turn is pivotally attached to a series of linksnot shown extending forward to links 39a and 39c and pivotally mountedbar 39b. Bar 3917 is controlled by the driver of the tractor by suitablepower means not shown but familiar in the industry.

A furrow forming apparatus, generally indicated by the numeral 50, isrigidly suspended beneath the frame 10 to plow and shape the furrow inwhich seed are later planted. The apparatus includes a wedge shaped plow52 the sides of which are pointed towards the front and inclinedinwardly at the bottom and which is rigidly supported from the frame bya curved brace 54 (FIG. 1) attached to transverse plow support 51. Theparticular apparatus, shape and employment shown and described hereinhave been successfully used to plant tomato seeds in the field chambersand the dimensions given are directed to that specific application andit should be understood that the depth and shape of the furrow will varydepending upon the soil, nature of plant and other considerations. Inthis embodiment the plow 52 is positioned so that approximately 4 inchesof its bottom surface enters the soil and as the frame advances, soilmounds 114 are formed rising about 3 inches above the level of the fieldas shown best in the sectional view in FIGS. 36. This forms a furrowhaving about 7 inches in total depth. Connected to the plow andextending rearwardly for the length of the vehicle is the furrow shapingstructure 56 having flat downwardly and inwardly sloping sides, asubstantially V-shaped cross section and a bottom opening between theinclined sides of about 3 inches and a top opening of about 14 inches,the angle of inclination of the sides being determined by thetypeof's'oil. In heavy soils the sides may be of greater inclinationbecause the earth holds its position after planting and sealing but inthe lighter or sandy soils a lesser inclination is required. Structure56 is rigidly suspended from the frame by a series of verticallyarranged angle irons 58 (only one of which is shown in FIG. 1 forsimplicity) and the rear portion of the structure includes a pair offlat, horizontal surfaces 112 (FIGS. 36) located along the top of thestructure which serve to support the mulch during the sealing operationas described below. It is readily apparent that movement of the plow 52and furrow shaping structure 56 across a field (to the left as shown inFIGS. 1 and 2) creates a continuous excavation in the soil which is ofsufficient depth and width to allow seeds to grow for an initialdevelopment period still totally below the surface of the field. Thestructure 56 shapes and maintains the position of the furrow sides whilethe various steps araccomplished and does not release the walls untilthe last step of compressing the soil on the film is completed. Althoughthe term furrow is used extensively in the specification to describe theexcavation formed in the soil, it is not intended to limit the inventionto a particular type or shape of soil chamber. For example, the depthand width of the furrow or soil chamber will depend to some extent uponthe type of soil and also upon the seed planted and the expectant rateof growth. The apparatus and furrow size shown herein as one embodimentof the invention has proved satisfactory for planting tomato seeds earlyin the Spring in the relatively heavy soil of northern Ohio.

After the furrow has been basically formed, various apparatus areemployed to prepare the soil in the bottom of the furrow for planting.In this embodiment, apparatus suitable for preparing the soil and forplanting tomato seeds is disclosed but such is merely representative ofthe apparatus which may operate in the machine disclosed for similarpurposes.

The soil at the bottom of the furrow is initially loosened by aprotruding point 55 of support 54 which penetrates the soil only an inchor so. After the soil is loosened, fertilizer is sprayed from nozzle 70through hose 72 from reservoir 74 mounted on the frame. Rate of feed ofthe fertilizer is controlled by rotation of ground wheel 78 conveyedthrough belt 77, transverse shaft 76 and belt 75 to the reservoir 74 asshown in FIG. 1.

A seeder generally designated by the numeral 60 and shown in FIGS. 1 and2, is suspended from the frame by adjustable members 62 and, in thisinstance, is positioned about 2 feet behind the leading point of theplow but substantially within the structure 56. The device shown is wellknown in the industry as a Planet Jr. planter manufactured by the L. S.Allen Company, Inc. of Philadelphia. Described generally, the

planter operates by a ground driven wheel 64 causing attached levers(not shown) to drop seeds S from a receptacle 66 in the soil at desiredintervals. A short piece of chain 68 drags over the seeds covering themwith soil.

Water is sprayed on the seeds through nozzle 88 from a tank 89 at apredetermined rate. Insecticide granules are dispersed into the furrowfrom a conduit from a reservoir 82 and the rate metered by belt 86 fromthe ground wheel 78. The granules are intended to kill insects which arepresent in or which may later gain access to the furrow. Finally, aherbicide to destroy weeds is sprayed over the soil in the furrowthrough a nozzle 93 along conduit 92 from a tank 90 similarly mounted onthe frame.

The preferred form of the mulch supply and mulch laying apparatus ofthis invention will now be described. In the embodiment disclosed, ithas been found advantageous to employ a polyethylene plastic film as aspecific type of mulch but other translucent or transparent, generallyimpervious materials of low cost would find suitable application. A rollof plastic film 100 having a width of about 25 inches and a diameter ofabout 9 inches is suspended for free rotation transverse to thelongitudinal axis of the vehicle on a pair of adjustable stanchions 102just above the top of the furrow. In this embodiment, the film F ispulled from the roll by the film itself being continuously sealed in thesoil as the vehicle progresses. For bulkier mulches, the roll may bepowered to provide an even flow without undue stresses being created onthe film. A particular type of film found satisfactory is marketed underthe name of Vita-Film, manufactured by Goodyear Tire & Rubber Company,having a gauge of 95-100 or thickness of 0.75-1 M. The location of thefilm roll in relation to the ground may be varied according to theheight of the soil mounds formed along the sides of the furrow but ithas been found advantageous to mount the source of film or mulch asclose as possible to the ground and avoid the necessity of additionalroller means to feed the film over the furrow.

To prepare the earth to receive the film, a pair of standard field discs110 each mounted on vertical bar 112 are positioned in the soil outsideof furrow-shaping structure 56 (FIG. 3) to form a pair of parallelgrooves in the soil mounds about 2 inches from each side of the furrow.The discs 110 are outwardly directed from the longitudinal axis of thevehicle to penetrate the soil to a depth of about 3 inches and displacesoil outwardly to form a pair of grooves 113 about 2 inches in width and3 inches in depth along and parallel to each side of the furrow. Ofcourse, the grooves can be of different dimension and location than thatdescribed. A pair of film wheels 106 supported for free rotation in thehorizontal stanchions 108 are positioned to advance within the grooves113 and press the extreme edges of the film into these grooves, the filmitself being. pulled downwardly into the grooves over the horizontalsupporting surfaces 112 of the structure 56 as shown in FIG. 4 which arelocated adjacent the highest level of the soil mounds 114. This pair ofsurfaces form the enlarged top edges of structure 56 and extendrearwardly to continually support the film .while the various filmsealing steps are occurring. Tension is normally expected to be createdon the film in a transverse direction by the pull of wheels 106 and inthe longitudinal direction by force exerted by that film portion alreadysecured in the soil. Surfaces 112 support the film F substantiallyparallel to the base of the furrow and at the same level as the top ofthe soil mounds 114 on the furrow sides while the film is pressed inboth grooves 113 and subsequently sealed in the-soil. Further, surfaces112 prevent the film from pulling down the earth mounds 114 into thefurrow, provide support when the mounds are broken or formed of clods,and act to prevent the film from being pulled out of the earth as thevehicle slightly changes direction. The surfaces 112 extend rearwardlyto support the film until each of three soil rendering operations arecompleted and the film is sealed in the soil as shown in FIGS. 3-6. As amodification of the supports 112, a transverse bar or surface extendingacross the furrow from the opposing sides of structure 56 and positionedimmediately behind the film supply 100 would effectively support thefilm as it was pressed into the soil.

Located immediately behind the film wheels 106 are a second pair ofinwardly directed soil discs 116 which penetrate the soil of the moundsto a depth similar to that of forward discs 110 and thereby displacesoil laterally onto the edges of the mulch film while said edges areheld down in grooves 113 by wheels 106. The light gauge of the filmallows it to be crinkled and deformed by the soil particles pressedagainst and into it thus increasing its retention in the soil. More thanone pair of soil discs 116 may be used to more effectively displace thesoil against the film in the groove as described.

Mounted for free rotation along the surface of the earth mounds behindthe soil discs 116 are a pair of inclined soil press wheels 120adjustably mounted in supports 122. The wheels 120 rotate and advancealong the outside surface of the soil mounds and pack the soil throwninwardly by the discs 116 against and on top of the edges of the plasticfilm. When the film is finally released by surfaces 112, the pressedearth on opposing top surfaces of the furrow mounds is quite suffcientto support the film across the open furrow even when object weighingseveral pounds are placed on it. It has been observed that as theweather hardens the soil, the mulch becomes locked in so tightly that itwill rip before it is pulled loose from the furrow mounds.

It has been found advantageous to place small holes or shaped slits atregularly spaced intervals along the center section of the mulch as itcovers the furrow to allow rain water to pass through to the plants andto allow a limited exchange of air. For this purpose, a pair of copperrods with electrically heated tips 131 are mounted for limited verticalmovement in relation to the film adjacent the film roll on arms 132which in turn are pivotally mounted on the frame and actuated by cams134. The cams 134 are rotated by ground wheel 78 and connecting belts 86and 133 so that as the vehicle advances the cams are rotated to causerods 130 to periodically lift and descend. As the tips 131 of the rods130 are electrically heated by current passing along wires 136 from asource, such as a generator not shown but mounted on the rear of theframe 10, longitudinal slits are formed in the film as it advances fromthe supply 100. In the preferred form, the slits measure about A inchesin width and 2 inches in length and are located about 5 inches apart sothat sufficient openings are provided for rain water to flow into thefurrow chamber even during heavy rain. It has also been foundadvantageous to cut the film along an are so that a small flap is formedwhich readily opens to let water through but closes to prevent flow ofair. Of course, mechanical means to slit the film with knives and pointsare available and preperforated film may be used so that no cutting isrequired. As a modification, it is found advantageous to initiallyutilize film with small slits while the weather is cold but then as theseason progresses, the slits could be enlarged or made more numerous toprovide increased ventilation.

In normal operation, the vehicle is positioned at one end of the fieldto be cultivated and the end of the mulch is secured in the soil byhand. The vehicle then begins to advance across the field either beingpulled or under its own power and automatically creates the furrow,prepares the soil, plants the seed and lays the film sealing it in thesoil along the sides of the furrow as described. When the end of the rowis reached, the mulch is cut and secured in the soil forming the closedchamber, and the frame 10 is raised by the hydraulic lift on the tractoreffecting the front of the vehicle and by the hydraulic assembly at therear of the vehicle thereby lifting the plow and furrow shapingstructure out of the soil. The vehicle is turned by movement of the rearwheels through the steering arms and positioned to form the next furrow.If the depth of the furrow is to be changed, then by rotation of eitheror both of cranks 30 the position of the plow 52 and structure 56 arevaried in relation to the frame and ground. As an obvious variation ofthe vehicle described, the frame 10 can successfully support a pair ofeach plows, furrow structure, mulch supply and apparatus for sealing thefilm similar to the single apparatus shown. With such apparatus thevehicle forms, plants and seals two chambers in the field at the sametime.

The mulch film is removed from the chambers when the seedlings are ofsufficient size and the season has progressed or the weather tempered tomake further environment control unnecessary. Of course the timingdepends upon the general weather conditions and location but it has beenfound generally satisfactory to remove the film in the latter part ofMay when planting in Ohio. One method for removing the film includesfreeing an end of the film from the soil and pulling it longitudinallythrough a ring which gathers the film into rope form increasing itstensile strength and allowing it to be wound up on a reel. This processcan economically be made part of a subsequent early Summer plantcultivation process in which the soil mounds are broken and displacedinto the furrow and around the stems of the growing plants. The filmitself can be reclaimed for further use or discarded.

It is one of the main advantages of this invention that use of thetransparent plastic film does not substantially retard solar energy frompassing into the soil and to the seedlings to create a hothouse effectso that the seeds germinate and plants develop earlier and at a fasterrate than those unprotected in the field. Similarly, the seeds andplants receive the natural supply of rain water and moisture evaporationfrom the soil is greatly reduced by the covering film. It is anotheradvantage of this invention that the growing season is effectivelyextended and risk of loss of crop or plant damage due to frost and otheradverse weather conditions is removed. Due to the protection afforded bythe field growth chamber as described, tests have shown that tomatoseeds may be planted in northern Ohio as early as about Apr. th whereasthe earliest safe planting time without the chamber was about May 10th.As an example of the effectiveness of the chamber in reducingtemperature extremes, after several days of below freezing temperaturesabove the ground in the early Spring, the temperature in the chambersdid not fall below 44 F. even though the days were cloudy. Of course, myinvention has equal application to vegetables and fruits other thantomatoes, and other crops such as corn and tobacco. Where the word seedis used in this specification and claims, it is understood to includevarious types of plant material, which are planted in the earth andexpected to develop further plant growth and fruit.

Of course, various modifications and changes in the preferred form ofthe apparatus and method of this invention as shown and described hereinwill be apparent to a skilled mechanic, but such modifications may bematters of form and convenience and will be within the scope of theappended claims.

I claim:

1. A machine for forming a plant growth chamber along the surface of afield comprising:

a frame adapted for movement in one direction across the a plow attachedto the frame having a portion located within the soil to form a furrowas the frame moves across the field;

a furrow-supporting structure extending rearwardly from the plow andattached to the frame, said structure having a pair of inclined sides tosubstantially maintain the shape of the furrow formed by the plow;

seed-planting means mounted on the frame for placing seeds in the bottomof the furrow;

a supply of substantially translucent mulch having a width greater thanthe width of the top of the furrow and having a length sufficient toextend at least a portion of the length of the furrow, said supply ofmulch being mounted on the frame and to the rear of said seed-plantingmeans to continuously lay a mulch strip over the top of the plantedfurrow as the frame moves across the field;

means mounted on the frame to the rear of the mulch supply and on bothsides of the furrow to press the edges of the mulch onto the opposingshoulders of said furrow;

means mounted on the frame located substantially level with the top ofthe furrow and shaped to support said mulch in a substantially tautcondition across the furrow as the mulch is pressed onto said furrowshoulders; and

means mounted on the frame for continuously sealing the opposing edgesof the mulch in the soil along the furrow shoulders while said mulch isbeing supported in said taut condition to form the plant growth chamber.

2. The machine as defined in claim 1 wherein the mulch is provided witha series of spaced apart holes extending generally lengthwise along thecenter of the'mulch so that after the mulch is laid over the top of thefurrow the holes permit the ingress of rain through the mulch and intothe furrow.

3. The machine as defined m claim .2 further including means mounted onthe frame in front of the mulch supply for placing fertilizer in thefurrow before the mulch is laid over the top of the furrow.

4. The machine as defined in claim 3 further including means mounted onthe frame in front of the mulch supply for placing insecticide in thefurrow before the mulch is laid over the top of the furrow.

5. The machine as defined in claim 4 further including means mounted onthe frame in front of the mulch supply fOl placing water in the furrowbefore the mulch is laid over the top of the furrow.

6. The machine as defined in claim 5 further including means mounted onthe frame to the rear of the mulch supply for placing herbicide in thefurrow at a location adjacent the rear of the frame and after the mulchis laid over the top of the furrow.

7. The machine as defined in claim 2 wherein the mulch is a transparentplastic film.

8. The machine as defined in claim 2 further including means mounted onthe frame in front of the mulch supply to form a pair of grooves in thesoil in the opposing shoulders of said furrow, the edges of the mulchbeing pressed into said grooves as the machine moves across the field.

9. The machine as defined in claim 8 further including means mounted onthe frame to the rear of the means for sealing the edges of the mulch inthe soil along the furrow shoulders for packing the soil on top of theedges of the mulch and thereby sealing the mulch in the opposingshoulders of the fur- TOW.

10. The machine as defined in claim 9 wherein the means for supportingthe mulch in said taut condition comprise a pair of horizontal surfacesmounted on the top of said sides of the furrow-supporting structure,said surfaces extending rearwardly from a location adjacent the mulchsupply to a location adjacent the means for packing the soil on themulch edges.

11. The machine as defined in claim 10 further including a pair ofwheels attached to and supporting the front of the frame and a pair ofwheels attached to and supporting the rear of the frame above thesurface of the field, and means connecting the wheels and the frame toallow the frame to be adjusted in height in relation to the surface ofthe field to thereby vary the depth of the furrow formed in the field asthe frame moves across the field.

12. The machine as defined in claim 11 further including at least onerod having a heated tip for forming spaced apart holes in the mulch,said rod being mounted on the frame to the rear of the mulch supply forgenerally vertical reciprocating movement in relation to the generallyhorizontal movement of the mulch so that the rod tip penetrates themulch at intervals to form spaced apart holes in the mulch laid over thetop of the furrow.

2. The machine as defined in claim 1 wherein the mulch is provided witha series of spaced apart holes extending generally lengthwise along thecenter of the mulch so that after the mulch is laid over the top of thefurrow the holes permit the ingress of rain through the mulch and intothe furrow.
 3. The machine as defined in claim 2 further including meansmounted on the frame in front of the mulch supply for placing fertilizerin the furrow before the mulch is laid over the top of the furrow. 4.The machine as defined in claim 3 further including means mounted on theframe in front of the mulch supply for placing insecticide in the furrowbefore the mulch is laid over the top of the furrow.
 5. The machine asdefined in claim 4 further including means mounted on the frame in frontof the mulch supply for placing water in the furrow before the mulch islaid over the top of the furrow.
 6. The machine as defined in claim 5further including means mounted on the frame to the rear of the mulchsupply for placing herbicide in the furrow at a location adjacent therear of the frame and after the mulch is laid over the top of thefurrow.
 7. The machine as defined in claim 2 wherein the mulch is atransparent plastic film.
 8. The machine as defined in claim 2 furtherincluding means mounted on the frame in front of the mulch supply toform a pair of grooves in the soil in the opposing shoulders of saidfurrow, the edges of the mulch being pressed into said grooves as themachine moves across the field.
 9. The machine as defined in claim 8further including means mounted on the frame to the rear of the meansfor sealing the edges of the mulch in the soil along the furrowshoulders for packing the soil on top of the edges of the mulch andthereby sealing the mulch in the opposing shoulders of the furrow. 10.The machine as defined in claim 9 wherein the means for supporting themulch in said taut condition comprise a pair of horizontal surfacesmounted on the top of said sides of the furrow-supporting structure,said surfaces extending rearwardly from a location adjacent the mulchsupply to a location adjacent the means for packing the soil on themulch edges.
 11. The machine as defined in claim 10 further including apair of wheels attached to and supporting the front of the frame and apair of wheels attached to and supporting the rear of the frame abovethe surface of the field, and means connecting the wheels and the frameto allow the frame to be adjusted in height in relation to the surfaceof the field to thereby vary the depth of the furrow formed in the fieldas the frame moves across the field.
 12. The machine as defined in claim11 further including at least one rod having a heated tip for formingspaced apart holes in the mulch, said rod being mounted on the frame tothe rear of the mulch supply for generally vertical reciprocatingmovement in relation to the generally horizontal movement of the mulchso that the rod tip penetrates the mulch at intervals to form spacedapart holes in the mulch laid over the top of the furrow.